Vessel sealing instrument

ABSTRACT

A bipolar electrosurgical instrument for clamping, grasping, manipulating, and sealing tissue includes first and second shafts each having a jaw member extending from a distal end thereof and a handle disposed at a proximal end thereof. The handle being operable to effect movement of the jaw members relative to one another from a first position wherein the jaw members are disposed in spaced relation relative to one another to a second position wherein the jaw members cooperate to grasp tissue therebetween. The bipolar instrument is connectable to a source of electrical energy having a first electrical potential connected to one of the jaw members and a second electrical potential connected to the other of the jaw members such that the jaw members are capable of selectively conducting energy through tissue held therebetween to effect a seal. Both the first and second electrical potentials are transmitted to the jaw members through the first shaft.

CROSS REFERENCE TO RELATED APPLICATIONS

[0001] This application is a continuation-in-part of PCT ApplicationSerial No. PCT/US01/11420 filed on Apr. 6, 2001 which is acontinuation-in-part of U.S. application Ser. No. 09/425,696 filed Oct.22, 1999 by Philip Mark Tetzlaff et al. which is a continuation-in-partof U.S. application Ser. No. 09/178,027 filed Oct. 23, 1998 by PhilipMark Tetzlaff et al., the entire contents of each of these applicationsare hereby incorporated by reference.

BACKGROUND

[0002] The present disclosure relates to forceps used for open surgicalprocedures. More particularly, the present disclosure relates to aforceps which applies a combination of mechanical clamping pressure andelectrosurgical current to seal tissue.

TECHNICAL FIELD

[0003] A hemostat or forceps is a simple plier-like tool which usesmechanical action between its jaws to constrict vessels and is commonlyused in open surgical procedures to grasp, dissect and/or clamp tissue.Electrosurgical forceps utilize both mechanical clamping action andelectrical energy to effect hemostasis by heating the tissue and bloodvessels to coagulate, cauterize and/or seal tissue.

[0004] Certain surgical procedures require sealing and cutting bloodvessels or vascular tissue. Several journal articles have disclosedmethods for sealing small blood vessels using electrosurgery. An articleentitled Studies on Coagulation and the Development of an AutomaticComputerized Bipolar Coagulator, J. Neurosurg., Volume 75, July 1991,describes a bipolar coagulator which is used to seal small bloodvessels. The article states that it is not possible to safely coagulatearteries with a diameter larger than 2 to 2.5 mm. A second article isentitled Automatically Controlled Bipolar Electrocoagulation—“COA-COMP”,Neurosurg. Rev. (1984), pp. 187-190, describes a method for terminatingelectrosurgical power to the vessel so that charring of the vessel wallscan be avoided.

[0005] By utilizing an electrosurgical forceps, a surgeon can eithercauterize, coagulate/desiccate, reduce or slow bleeding and/or sealvessels by controlling the intensity, frequency and duration of theelectrosurgical energy applied to the tissue. Generally, the electricalconfiguration of electrosurgical forceps can be categorized in twoclassifications: 1) monopolar electrosurgical forceps; and 2) bipolarelectrosurgical forceps.

[0006] Monopolar forceps utilize one active electrode associated withthe clamping end effector and a remote patient return electrode or padwhich is typically attached externally to the patient. When theelectrosurgical energy is applied, the energy travels from the activeelectrode, to the surgical site, through the patient and to the returnelectrode.

[0007] Bipolar electrosurgical forceps utilize two generally opposingelectrodes which are disposed on the inner opposing surfaces of the endeffectors and which are both electrically coupled to an electrosurgicalgenerator. Each electrode is charged to a different electric potential.Since tissue is a conductor of electrical energy, when the effectors areutilized to grasp tissue therebetween, the electrical energy can beselectively transferred through the tissue.

[0008] In order to effect a proper seal with larger vessels, twopredominant mechanical parameters must be accurately controlled—thepressure applied to the vessel and the gap between the electrodes bothof which affect thickness of the sealed vessel. More particularly,accurate application of the pressure is important to oppose the walls ofthe vessel, to reduce the tissue impedance to a low enough value thatallows enough electrosurgical energy through the tissue, to overcome theforces of expansion during tissue heating and to contribute to the endtissue thickness which is an indication of a good seal. It has beendetermined that a fused vessel wall is optimum between 0.001 and 0.005inches. Below this range, the seal may shred or tear and above thisrange the lumens may not be properly or effectively sealed.

[0009] With respect to smaller vessel, the pressure applied to thetissue tends to become less relevant whereas the gap distance betweenthe electrically conductive surfaces becomes more significant foreffective sealing. In other words, the chances of the two electricallyconductive surfaces touching during activation increases as the vesselsbecome smaller.

[0010] Electrosurgical methods may be able to seal larger vessels usingan appropriate electrosurgical power curve, coupled with an instrumentcapable of applying a large closure force to the vessel walls. It isthought that the process of coagulating small vessels is fundamentallydifferent than electrosurgical vessel sealing. For the purposes herein,“coagulation” is defined as a process of desiccating tissue wherein thetissue cells are ruptured and dried and vessel sealing is defined as theprocess of liquefying the collagen in the tissue so that it reforms intoa fused mass. Thus, coagulation of small vessels is sufficient topermanently close them. Larger vessels need to be sealed to assurepermanent closure.

[0011] Numerous bipolar electrosurgical forceps have been proposed inthe past for various open surgical procedures. However, some of thesedesigns may not provide uniformly reproducible pressure to the bloodvessel and may result in an ineffective or non-uniform seal. Forexample, U.S. Pat. No. 2,176,479 to Willis, U.S. Pat. Nos. 4,005,714 and4,031,898 to Hiltebrandt, U.S. Pat. Nos. 5,827,274, 5,290,287 and5,312,433 to Boebel et al., U.S. Pat. Nos. 4,370,980, 4,552,143,5,026,370 and 5,116,332 to Lottick, U.S. Pat. No. 5,443,463 to Stern etal., U.S. Pat. No. 5,484,436 to Eggers et al. and U.S. Pat. No.5,951,549 to Richardson et al., all relate to electrosurgicalinstruments for coagulating, cutting and/or sealing vessels or tissue.

[0012] Many of these instruments include blade members or shearingmembers which simply cut tissue in a mechanical and/or electromechanicalmanner and are relatively ineffective for vessel sealing purposes. Otherinstruments rely on clamping pressure alone to procure proper sealingthickness and are not designed to take into account gap tolerancesand/or parallelism and flatness requirements which are parameters which,if properly controlled, can assure a consistent and effective tissueseal. For example, it is known that it is difficult to adequatelycontrol thickness of the resulting sealed tissue by controlling clampingpressure alone for either of two reasons: 1) if too much force isapplied, there is a possibility that the two poles will touch and energywill not be transferred through the tissue resulting in an ineffectiveseal; or 2) if too low a force is applied, a thicker less reliable sealis created.

[0013] As mentioned above, in order to properly and effectively seallarger vessels, a greater closure force between opposing jaw members isrequired. It is known that a large closure force between the jawstypically requires a large moment about the pivot for each jaw. Thispresents a challenge because the jaw members are typically affixed withpins which are positioned to have a small moment arms with respect tothe pivot of each jaw member. A large force, coupled with a small momentarm, is undesirable because the large forces may shear the pins. As aresult, designers must compensate for these large closure forces byeither designing instruments with metal pins and/or by designinginstruments which at least partially offload these closure forces toreduce the chances of mechanical failure. As can be appreciated, ifmetal pivot pins are employed, the metal pins must be insulated to avoidthe pin acting as an alternate current path between the jaw memberswhich may prove detrimental to effective sealing.

[0014] Increasing the closure forces between electrodes may have otherundesirable effects, e.g., it may cause the opposing electrodes to comeinto close contact with one another which may result in a short circuitand a small closure force may cause pre-mature movement of the issueduring compression and prior to activation.

[0015] Thus, a need exists to develop a bipolar forceps whicheffectively seals vascular tissue and solves the aforementioned problemsby providing an instrument which enables a large closure force betweenthe opposing jaws members, reduces the chances of short circuiting theopposing jaws during activation and assists in manipulating, grippingand holding the tissue prior to and during activation.

SUMMARY

[0016] The present disclosure relates to a bipolar electrosurgicalinstrument for use in open surgery which includes first and secondshafts one of which is connectable to a source of electrosurgicalenergy. Each shaft includes a jaw member extending from a distal endthereof and a handle disposed at a proximal end thereof for effectingmovement of the jaw members relative to one another from a first, openposition wherein the jaw members are disposed in spaced relationrelative to one another to a second, closed position wherein the jawmembers cooperate to grasp tissue therebetween. The source of electricalenergy effects first and second electrical potentials in the respectivejaw members such that the jaw members are capable of selectivelyconducting energy through tissue held therebetween to effect a seal.

[0017] Preferably, the first and second electrical potentials arecreated at the jaw members through the first shaft. For example, in oneembodiment, the first electrical potential is transmitted through thefirst shaft by a lead having a terminal end which electricallyinterfaces with a distal connector which connects a first jaw member tothe first electrical potential. The second electrical potential istransmitted through the first shaft by a tube disposed within the firstshaft which connects the second jaw member to the second electricalpotential.

[0018] The first and second jaw members are connected about a pivot pin.The distal connector is preferably interposed between the jaw membersand includes a series of flanges which are dimensioned to prevent theemanation of stray currents from the electrically conductive sealingsurfaces of the jaw members during activation.

[0019] Preferably, the distal connector includes a spring washer or wavewasher which acts as an electrical intermediary between the terminal endand the jaw member. In one embodiment, the spring washer is beveled toenhance the electrical interface between the terminal end and the jawmember, i.e., beveling causes the spring washer to rotate relative theterminal end during movement of the jaw members from the first to secondpositions which provides a self-cleaning, enhanced running electricalcontact between the terminal end and the jaw member.

[0020] Preferably, the distal connector is made from an insulativesubstrate and is disposed between the jaw members for electricallyisolating the first and second potentials. In one embodiment, the distalconnector includes a first surface having at least one recess definedtherein which is dimensioned to receive at least a portion of theterminal end of the lead.

[0021] In yet another embodiment, one of the jaw members includes askirt which is dimensioned to prevent exposure of the terminal endduring all angles of operation, i.e., when the jaw members are disposedin the first position, the second position and/or during operativemovement therebetween.

[0022] The lead preferably includes a inner core made from a solid ormulti-strand electrically conductive material, e.g., copper/aluminumwire, which is surrounded by an insulative, non-conductive coating,e.g., plastic. In one embodiment, the terminal or distal end of theelectrically conductive material is flattened, i.e., “flat-formed”, andis dimensioned to substantially encircle a boss which extends from thesurface of the distal connector. Preferably, the boss is designed toelectrically insulate the terminal end of the lead from the pivot pin.

[0023] In another embodiment, at least one non-conductive stop member isdisposed on an electrically conductive sealing surface of one of the jawmembers. The stop members are designed to control/regulate the distance,i.e., gap, between the jaw members when tissue is held therebetweenduring activation.

BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Various embodiments of the subject instrument are describedherein with reference to the drawings wherein:

[0025]FIG. 1 is a left, perspective view of a forceps according to thepresent disclosure;

[0026]FIG. 2 is an enlarged, perspective view of an end effectorassembly of the forceps of FIG. 1 shown in open configuration;

[0027]FIG. 2′ is an enlarged view of the distal end of a bipolarinstrument incorporated by reference from a prior disclosure;

[0028]FIG. 3 is an enlarged, perspective view of the end effectorassembly of the forceps of FIG. 1 shown in closed configuration;

[0029]FIG. 4A is an exploded view of the forceps according to thepresent disclosure;

[0030]FIG. 4B is an enlarged, exploded view of the end effector assemblyof FIG. 4A showing the electrical connection of a distal electricalconnector for supplying electrical energy to the end effector assembly;

[0031]FIG. 4′ is an enlarged, exploded view of the end effector assemblyof a bipolar instrument incorporated by reference from a priordisclosure;

[0032]FIG. 5 is an enlarged, top perspective view of a lower jaw memberof forceps with the distal connector seated thereon;

[0033]FIG. 5′ is an enlarged view of a distal end of a bipolarinstrument incorporated by reference from a prior disclosure;

[0034]FIG. 6 is a right, perspective view of the forceps of FIG. 1 showngrasping a tissue structure;

[0035]FIG. 6A′-6G′ are enlarged views of jaw members and stopconfigurations of a bipolar instrument incorporated by reference from aprior disclosure;

[0036]FIG. 7 is a enlarged view of the indicated area of detail in FIG.4A showing a proximal electrical interface/connector for supplyingelectrical energy to the end effector assembly; and

[0037]FIG. 8 is a cross section of the forceps of FIG. 6 showing theelectrical feed path of a first lead having a first electrical potentialand showing the electrical connection of the proximal electricalinterface of FIG. 7 with a second lead having a second electricalpotential.

DETAILED DESCRIPTION

[0038] Referring now to FIGS. 1-4, a forceps 10 for use with opensurgical procedures includes elongated shaft portions 12 a and 12 b eachhaving a proximal end 16 a and 16 b, respectively, and a distal end 14 aand 14 b, respectively. In the drawings and in the descriptions whichfollow, the term “proximal”, as is traditional, will refer to the end ofthe forceps 10 which is closer to the user, while the term “distal” willrefer to the end which is further from the user.

[0039] The forceps 10 includes an end effector assembly 100 whichattaches to distal ends 14 a and 14 b of shafts 12 a and 12 b,respectively. As explained in more detail below, the end effectorassembly 100 includes pair of opposing jaw members 110 and 120 which arepivotably connected about a pivot pin 150.

[0040] Preferably, each shaft 12 a and 12 b includes a handle 17 a and17 b disposed at the proximal end 16 a and 16 b thereof which eachdefine a finger hole 18 a and 18 b, respectively, therethrough forreceiving a finger of the user. As can be appreciated, finger holes 18 aand 18 b facilitate movement of the shafts 12 a and 12 b relative to oneanother which, in turn, pivot the jaw members 110 and 120 from an openposition (FIG. 2) wherein the jaw members 110 and 120 are disposed inspaced relation relative to one another to a clamping or closed position(FIG. 3) wherein the jaw members 110 and 120 cooperate to grasp tissue400 (FIG. 6) therebetween.

[0041] A ratchet 30 is preferably included for selectively locking thejaw members 110 and 120 relative to one another at various positionsduring pivoting. As best shown in FIG. 6, a first ratchet interface,e.g., 30 a, extends from the proximal end 16 a of shaft member 12 atowards a second ratchet interface 30 b in a generally verticallyaligned manner such that the inner facing surfaces of each ratchet 30 aand 30 b abut one another upon closure about the tissue 400. Preferably,each ratchet interface 30 a and 30 b includes a plurality of flanges 32a and 32 b, respectively, which projects from the inner facing surfaceof each ratchet interface 30 a and 30 b such that the ratchet interfaces30 a and 30 b interlock in at least one position. In the embodimentshown in FIG. 6, the ratchet interfaces 30 a and 30 b interlock atseveral different positions.

[0042] Preferably, each position associated with the cooperating ratchetinterfaces 30 a and 30 b holds a specific, i.e., constant, strain energyin the shaft members 12 a and 12 b which, in turn, transmits a specificclosing force to the jaw members 110 and 120. It is envisioned that theratchet 30 may include graduations or other visual markings which enablethe user to easily and quickly ascertain and control the amount ofclosure force desired between the jaw members. A design without aratchet system or similar system would require the user to hold the jawmembers 110 and 120 together by applying constant force to the handles17 a and 17 b which may yield inconsistent results.

[0043] As best illustrated in FIG. 1, one of the shafts, e.g., 12 b,includes a proximal shaft connector 19 which is designed to connect theforceps 10 to a source of electrosurgical energy such as anelectrosurgical generator (not shown). More particularly, proximal shaftconnector 19 is formed by a cover 19 a and a flange 19 b which extendsproximally from shaft 12 b. Preferably, cover 19 a and flange 19 bmechanically cooperate to secure an electrosurgical cable 210 to theforceps 10 such that the user may selectively apply electrosurgicalenergy as needed.

[0044] The proximal end of the cable 210 includes a plug 200 having apair of prongs 202 a and 202 b which are dimensioned to electrically andmechanically engage the electrosurgical energy generator. As explainedin more detail below with respect to FIG. 8, the distal end of the cable210 is secured to the proximal shaft connector 19 of shaft 12 b by aplurality of finger-like clamping members 77 a and 77 b and a cablecrimp having opposing fingers 76 a and 76 b. The interior of cable 210houses a pair of leads 210 a and 210 b which conduct the differentelectrical potentials from the electrosurgical generator to the jawmembers 110 and 120 as explained in greater detail below.

[0045] As best seen in FIGS. 2-4B, the two opposing jaw members 110 and120 of the end effector assembly 100 are pivotable about pin 150 fromthe open position to the closed position for grasping tissue 400therebetween. Jaw members 110 and 120 are generally symmetrical andinclude similar component features which cooperate to permit facilerotation about pivot pin 150 to effect the grasping and sealing oftissue 400. As a result and unless otherwise noted, jaw member 110 andthe operative features associated therewith will initially be describedherein in detail and the similar component features with respect to jawmember 120 will be briefly summarized thereafter.

[0046] Jaw member 110 includes an insulated outer housing 114 which isdimensioned to mechanically engage an electrically conductive sealingsurface 112 and a proximally extending flange 130 which is dimensionedto seat a distal connector 300 which is described in more detail belowwith respect to FIGS. 4A, 4B and 5. Preferably, outer insulative housing114 extends along the entire length of jaw member 110 to reducealternate or stray current paths during sealing and/or incidentalburning of tissue 400. The inner facing surface of flange 130 includesan electrically conductive plate 134 (FIG. 4B) which conductselectrosurgical energy to the electrically conductive sealing surface112 upon activation.

[0047] Likewise, jaw member 120 include similar elements which include:an outer housing 124 which engages an electrically conductive sealingsurface 122; a proximally extending flange 140 which seats the oppositeface of the distal connector 300; an electrically conductive plate 144which conducts electrosurgical energy to the electrically conductivesealing surface 122 upon activation.

[0048] It is envisioned that one of the jaw members, e.g., 110, includesat least one stop member 150 disposed on the inner facing surface of theelectrically conductive sealing surface 112 (and/or 122). Alternativelyor in addition, the stop member 150 may be positioned adjacent to theelectrically conductive sealing surfaces 112, 122 or proximate the pivotpin 151. The stop member(s) is preferably designed to facilitategripping and manipulation of tissue 400 and to define a gap “G” (FIG. 6)between opposing jaw members 110 and 120 during sealing. Preferably theseparation distance during sealing or the gap distance “G” is within therange of about 0.001 inches (˜0.03 millimeters) to about 0.006 inches(˜0.016 millimeters).

[0049] A detailed discussion of these and other envisioned stop members150 as well as various manufacturing and assembling processes forattaching, disposing, depositing and/or affixing the stop members 150 tothe electrically conductive sealing surfaces 112, 122 are described incommonly-assigned, co-pending PCT Application Serial No. PCT/US01/11222entitled “BIPOLAR ELECTROSURGICAL FORCEPS WITH NON-CONDUCTIVE STOPMEMBERS” which is hereby incorporated by reference in its entiretyherein. For the purposes of this disclosure at least the following textfrom PCT/US01/11222 is included herein. Corresponding reference numeralto the present disclosure are enclosed between parentheses “( )” for thepurposes of clarity. In addition, FIGS. 2, 4, 15B and 16A-16G from theabove disclosure are incorporated herein and renumbered as FIGS. 2′, 4′,5′ and 6A′-6G′ for the purposes of clarity. The reference numeralsassociated with these figures also include a prime “′” designation forthe purposes of clarity, e.g., 80′, 82′, etc.

[0050] As mentioned above, two mechanical factors play an important rolein determining the resulting thickness of the sealed tissue andeffectiveness of the seal, i.e., the pressure applied between opposingjaw members 80′ and 82′ (110 and 120) and the gap between the opposingjaw members 80′ and 82′ (110 and 120) during the sealing process.However, thickness of the resulting tissue seal cannot be adequatelycontrolled by force alone. In other words, too much force and the twojaw members 80′ and 82′ (110 and 120) would touch and possibly shortresulting in little energy traveling through the tissue thus resultingin a bad seal. Too little force and the seal would be too thick.

[0051] Applying the correct force is also important for other reasons:to oppose the walls of the vessel; to reduce the tissue impedance to alow enough value that allows enough current through the tissue; and toovercome the forces of expansion during tissue heating in addition tocontributing towards creating the required end tissue thickness which isan indication of a good seal.

[0052] Preferably, the seal surfaces or tissue contacting surfaces 151′,251′ (112,122) (See renumber FIGS. 5′ and 6A′-6G′) of the jaw members80′ and 82′ (110 and 120) are relatively flat to avoid currentconcentrations at sharp edges and to avoid arcing between high points.In addition and due to the reaction force of the tissue 150 whenengaged, jaw members 80′ and 82′ (110 and 120) are preferablymanufactured to resist bending. For example and as best seen in FIGS. 2′and 6A′-6G′, the jaw members 80′ and 82′ (110 and 120) are preferablytapered along width “W” which is advantageous for two reasons: 1) thetaper will apply constant pressure for a constant tissue thickness atparallel; 2) the thicker proximal portion of the jaw members 80′ and 82′(110 and 120) will resist bending due to the reaction force of thetissue 150.

[0053] As best seen in FIG. 4′, in order to achieve a desired gap range(e.g., about 0.001 to about 0.005 inches and preferably about 0.002inches to about 0.003 inches) and apply a desired force to seal thetissue, at least one jaw member 80′ and/or 82′ (110 and 120) includes astop member 139′ (150) which limits the movement of the two opposing jawmembers 80′ and 82′ (110 and 120) relative to one another. Preferably,stop member 139′ (150) extends from the sealing surface or tissuecontacting surface 151′ (112 or 122) a predetermined distance accordingto the specific material properties (e.g., compressive strength, thermalexpansion, etc.) to yield a consistent and accurate gap distance duringsealing.

[0054] As explained above, in some cases it may be preferable todimension stake 119′ such that it acts like a stop member and/or anadditional stop member and also controls/limits the movement of the twoopposing jaw members 80′ and 82′ (110 and 120) relative to one another.Preferably, stop member 139′ (150) and/or stake 119′ is made from aninsulative material, e.g., parylene, nylon and/or ceramic and isdimensioned to limit opposing movement of the jaw members 80′ and 82′(110 and 120) to within the above gap range.

[0055]FIG. 4A shows an exploded view of the various components of theforceps 10 and the inter-operative relationships among the same. Moreparticularly and in addition to the components described above withrespect to FIGS. 1-3 above, shaft 12 a is preferably hollow to define alongitudinal channel 15 a disposed therethrough which is dimensioned toreceive a tube 60 a therein. Tube 60 a includes a proximal end 64 a, adistal end 62 a and at least one mechanical interface 61 a disposedtherebetween. Shaft 12 a also includes a cover plate 50 which isdesigned for snap-fit engagement within an aperture/cavity 45 a definedthrough the outer surface of shaft 12 a. Cover plate 50 includes aseries of opposing flanges 51 a and 51 b which extend therefrom whichare dimensioned to secure the tube 60 a within shaft 12 a as describedbelow. A second flange 52 secures the cover plate 50 to the shaft 12 a.

[0056] During assembly, the proximal end 64 a of tube 60 a is slideableincorporated within channel 15 a such that mechanical interface 61 a ispoised for engagement with cover plate 50. Cover plate 50 is thensnapped into cavity 45 a such that flanges 51 a and 51 b secure tube 60a within shaft 12 a. It is envisioned that the cavity 45 a of shaft 12 amay include at least one detent (not shown) which engages mechanicalinterface 61 a disposed along the outer surface of tube 60 a tolimit/prevent rotation of the tube 60 a relative to the shaft 12 a. Thiscooperative relationship is shown by way of example with respect todetents 75 a and 75 b and interfaces (e.g., notches) 61 b of shaft 12 bin FIG. 8. In this instance, flanges 51 a and 51 b (much like flanges 42a and 42 b of cover plate 40 in FIG. 8) hold the detents 75 a and 75 bin FIG. 8) in secure engagement within the notch(es) 61 a to preventrotational and/or longitudinal movement of the tube 60 a within thechannel 15 a.

[0057] Preferably, the proximal-most end of tube 60 a includes aslit-like interface 65 a which mechanically engages a correspondingtongue 88 a extending from the inner surface of shaft 12 a within cavity45 a. It is envisioned that tongue 88 a also prevents rotationalmovement of the tube 60 a within the shaft 12 a. Alternatively, slit 65a may be formed to allow radial contraction and expansion of the tube 60a to promote friction-fit engagement between the tube 60 a and the shaft12 a. Other interfaces are also envisioned which will facilitateengagement of the shaft 12 a and the tube 60 a, e.g., snap-fit,spring-lock, locking tabs, screw-like interface, tongue and groove, etc.

[0058] The distal end 62 a of tube 60 a is preferably dimensioned toengage jaw member 120, i.e., the distal end 62 a includes a slit-likeinterface 66 a which promotes simple, secure friction-fit engagement ofthe tube 60 a with the jaw member 120. More particularly and asmentioned above, jaw member 120 includes a proximally extending flange130 having a sleeve 128 extending proximally therefrom which isdimensioned such that, upon insertion of the sleeve 128 within distalend 62 a, slit-like interface 66 a expands radially outwardly andsecurely locks the jaw member 120 to tube 60 a. Again, other methods ofattachment are also envisioned which would serve the same purpose, e.g.,snap-locks, locking tabs, spring-locks, screw-like interface, tongue andgroove, etc.

[0059] As can be appreciated by the present disclosure, the arrangementof shaft 12 b is slightly different from shaft 12 a as shown best inFIGS. 4B, 7 and 8. More particularly, shaft 12 b is also hollow todefine a channel 15 b therethrough and is dimensioned to receive a tube60 b therein. Tube 60 b includes a proximal end 64 b and a distal end 62b which attach in a generally similar fashion as their counterpartcomponents with respect to shaft 12 a. For example, the proximal end 64b of tube 60 b is slideable incorporated within channel 15 b such that amechanical interface 61 b disposed on the outer surface of tube 60 b ispoised for engagement with a cover plate 40 (FIGS. 4A and 8).

[0060] Preferably and since the forceps 10 is uniquely designed toincorporate all of the electrical interfaces and connections within andalong a single shaft, e.g., 12 b, shaft 12 b includes a slightly largercavity 45 b defined therein for housing and securing the variouselectrical connections associated with the forceps 10 as describedbelow. For example, cover plate 40 is dimensioned slightly differentlythan cover plate 50 mostly due to the spatial considerations which mustbe taken into account for incorporation of the various internallydisposed electrical connections. However, cover plate 40 does snap atopshaft 12 b such that a pair of flanges 42 a and 42 b secure tube 60 bwithin shaft 12 b in a similar manner as described above. For example,FIG. 8 shows a pair of detents 75 a and 75 b disposed within the cavity45 b of shaft 12 b which engage a corresponding number of mechanicalinterfaces 61 b disposed along the outer surface of tube 60 b tolimit/prevent rotation of the tube 60 b relative to the shaft 12 b. Whenassembled, each flange 42 a and 42 b is pushed into a correspondinggroove 73 a and 73 b, respectively, which effectively maintain/hold thedetents 75 a and 75 b in secure engagement within the notches 61 b toprevent rotational and/or longitudinal movement of the tube 60 b withinthe channel 15 b.

[0061] End 64 b of tube 60 b also includes a slit-like interface 65 bwhich mechanically engages a corresponding tongue 88 b extending fromthe inner surface of shaft 12 b within cavity 45 b. It is envisionedthat tongue 88 a also prevents rotational movement of the tube 60 bwithin the shaft 12 b. Alternatively, slit 65 b may be formed to allowradial contraction and expansion of the tube 60 b to promotefriction-fit engagement between the tube 60 b and the shaft 12 b.

[0062] Unlike tube 60 a, tube 60 b is designed as an electrical conduitfor transmitting electrosurgical energy to jaw member 110 which isexplained in more detail below with respect to FIGS. 7 and 8. The distalend 62 b of tube 60 b is preferably dimensioned to engage jaw member110, i.e., the distal end 62 b includes a slit-like interface 66 b whichpromotes simple, secure friction-fit engagement of the tube 60 b withthe jaw member 110. This is best illustrated in FIG. 4B which showsproximally extending flange 130 of jaw member 110 having a terminalsleeve 138 which extends therefrom. Terminal sleeve 138 is dimensionedsuch that, upon insertion of the terminal sleeve 138 within distal end62 b, slit-like interface 66 b expands radially outwardly and securelylocks the jaw member 110 to tube 60 b.

[0063] As can be appreciated, terminal end 138 is at least partiallymade from an electrically conductive material such that anelectrosurgical potential is effectively conducted from the tube 60 b,through the terminal sleeve 138, across plate 134 and to theelectrically conductive sealing plate 112 upon activation. As mentionedabove, the outer insulative housing 114 of jaw member 110 effectivelyeliminates stray electrical currents and incidental burning of tissueacross the intended electrical path.

[0064] As best shown in FIG. 4B, jaw member 110 includes a raceway 135extending proximally from the flange 130 which includes terminal sleeve138 at the proximal-most end thereof. The terminal sleeve 138 connectsto the conductive tube 60 b disposed within shaft 12 b as describedabove. Raceway 135 serves two purposes: 1) to provide electricalcontinuity from the terminal sleeve 138, through the electricallyconductive plate 134 and to the electrically conductive sealing surface112; and 2) to provide a channel for guiding lead 210 a to the distalconnector 300 as described below.

[0065] Insulated outer housing 114 is dimensioned to securely engage theelectrically conductive sealing surface 112. It is envisioned that thismay be accomplished by stamping, by overmolding, by overmolding astamped electrically conductive sealing plate and/or by overmolding ametal injection molded seal plate. All of these manufacturing techniquesproduce an electrode having an electrically conductive surface 112 whichis substantially surrounded by an insulated outer housing 114.

[0066] It is envisioned that the jaw member may also include a secondinsulator (not shown) disposed between the electrically conductivesealing surface 112 and the outer insulative housing 114. The insulatedouter housing 114 and the electrically conductive sealing surface 112(and the other insulator if utilized) are preferably dimensioned tolimit and/or reduce many of the known undesirable effects related totissue sealing, e.g., flashover, thermal spread and stray currentdissipation.

[0067] It is also envisioned that the electrically conductive sealingsurface 112 may include a pinch trim (not shown) which facilitatessecure engagement of the electrically conductive surface 112 to theinsulated outer housing 114 and also simplifies the overallmanufacturing process. It is also contemplated that the electricallyconductive sealing surface 112 may include an outer peripheral edgewhich has a radius and the insulated outer housing 114 meets theelectrically conductive sealing surface 112 along an adjoining edgewhich is generally tangential to the radius and/or meets along theradius. Preferably, at the interface, the electrically conductivesurface 112 is raised relative to the insulated outer housing 114. Theseand other envisioned embodiments are discussed in concurrently-filed,co-pending, commonly assigned Application Serial No. PCT/US01/11412entitled “ELECTROSURGICAL INSTRUMENT WHICH REDUCES COLLATERAL DAMAGE TOADJACENT TISSUE” by Johnson et al. and concurrently-filed, co-pending,commonly assigned Application Serial No. PCT/US01/11411 entitled“ELECTROSURGICAL INSTRUMENT WHICH IS DESIGNED TO REDUCE THE INCIDENCE OFFLASHOVER” by Johnson et al.

[0068] As best illustrated in the exploded view of FIG. 4B, the innerperiphery of tube 60 b is preferably dimensioned to house lead 210 atherethrough such that a different electrically potential can beeffectively transmitted to jaw member 120. More particularly and asmentioned above, cable 210 houses two leads 210 a and 210 b havingdifferent electrical potentials. The first lead 210 a is disposedthrough tube 60 b and conducts the first electrical potential to jawmember 120 as described in more detail below. The second lead 210 b iselectrically interfaced with tube 60 b at a proximal connector 80 (FIG.7) which includes a series of electrical crimps 85, 87 and 89 forsecuring lead 210 b to tube 60 b. As a result, tube 60 b carries thesecond electrical potential therethrough for ultimate connection to jawmember 110 as described above.

[0069] Lead 210 a preferably includes an insulative coating 213 whichsurrounds an inner core or electrical conductor 211 (e.g., wire)disposed therein to insulate the electrical conductor 211 from the tube60 b during activation. It is envisioned that the wire 211 may be madefrom a solid or multi-strand electrically conductive material, e.g.,copper/aluminum, which is surrounded by an insulative, non-conductivecoating 213, e.g., plastic.

[0070] The wire 211 includes a terminal end 212 which is dimensioned toelectrically interface with jaw member 120. Preferably, the terminal end212 is “flat-formed” in a generally arcuate shape to encircle acorresponding boss 314 which extends upwardly from the distal connector300 towards jaw member 120 as described below. It is envisioned that thedistal connector 300 performs at least two functions: 1) to insulate jawmember 110 from jaw member 120; and 2) to provide a running electricalconnection for lead 210 a to jaw member 120.

[0071] More particularly, the distal connector 300 is generally shapedto match the overall profile of the electrically conductive face plates134 and 144 of jaw members 110 and 120, respectively, such that, uponassembly, outer facing surfaces 302 and 304 of the distal connector 300abut against the corresponding plates 134 and 144 of jaw member 110 and120, respectively. It is envisioned that the outer facing surface 302 ofthe distal connector 300 acts as a runway surface which facilitatespivotable motion of jaw member 120 about pivot pin 151 relative to jawmember 110. Preferably, the distal connector 300 is made form aninsulative substrate such as plastic or some other non-conductivematerial.

[0072] The distal connector includes a series of flanges 322 and 326which extend towards jaw member 120 and a second series of flanges 324and 328 which extend towards jaw member 110. It is envisioned that theseflanges 322, 324, 326 and 328 insulate the other operative components ofthe forceps 10 and the patient from stray electrical currents emanatingfrom the electrically conductive plates 134 and 144 during activation.Flanges 322 and 328 may also be dimensioned to limit/restrict theexpansion of tissue 400 beyond the sealing surfaces 112 and 122 duringactivation. Flanges 326 and 324 are preferably dimensioned to insulatethe forceps during all angles of operation, i.e., pivoting of the jawmembers 110 and 120.

[0073] As mentioned above, the distal connector 300 includes a boss 314which extends towards jaw member 120 which is dimensioned to secure theterminal end 212 of lead 210 a. Preferably, the boss is designed toelectrically insulate the terminal end of the lead from the pivot. Theboss 314 preferably defines an aperture 316 therethrough for receivingthe pivot pin 151 and to allow pivotable motion of jaw member 120 aboutthe pivot 151 and the boss 314 relative to jaw member 110.

[0074] A continuous series of recesses 312, 318 and 319 are formedaround and proximate boss 314 to seat the flat-formed terminal end 212,the wire 211 and the insulated portion of the lead 210 a, respectively.This also secures lead 210 a to the distal connector and limits movementof the same (210 a). In some cases it may be preferable to include adollop of silicone or other non-conductive material at the junctionbetween the wire and the terminal end 212 as an added and/or alternativeinsulating safeguard. It is also envisioned that flange 326 may includea notch (not shown) disposed therethrough which facilitates assembly ofthe lead 210 a atop the distal connector 300. As can be appreciated,this eliminates the step of forming the arcuately-shaped terminal end212 after insertion through channel 318. As mentioned above, a dollop ofsilicone or the like may be added atop/within the notch for insulationpurposes after the terminal end 212 is seated within the distalconnector 300.

[0075] The proximal-most portion of distal connector 300 includes afinger 320 which is dimensioned to seat within a channel 137 formedwithin the raceway 135 such that the distal connector 300 moves inconnection with jaw member 110 during pivoting. Channel 135 may beformed during a molding process, subsequently bored after the raceway135 is formed or by any other known method of formation. The uppermostedge of boss 314 is preferably dimensioned to seat within acorresponding recess (not shown) formed within plate 144. Likewise andalthough not shown, it is envisioned that the opposite end of boss 314extends towards plate 134 and seats within a recess 131 formed withinplate 134. It is envisioned that recess 131 promotes engagement of thedistal connector 300 with the jaw member 110.

[0076] The distal connector 300 also includes a spring washer or wavewasher 155 which is preferably dimensioned to encircle the boss 314 atopterminal end 212. Upon assembly, the washer 212 is sandwiched/wedgedbetween the terminal end 212 and the conductive plate 144 of jaw member120. It is envisioned that the washer 155 enhances the connectionbetween the terminal end and the plate 144. More particularly, thewasher 155 is preferably shaped such that the washer 155 provides aself-cleaning, running electrical contact between the terminal end 212and the jaw member 120. It is contemplated that the washer 155“self-cleans” due to the frictional contact and relative movement of thewasher 155 with respect to the terminal end 212 during pivoting of thejaw members 110 and 120. The self-cleaning action can be attributed tothe washer 155 rubbing, scoring and/or digging against the terminal end212 and/or the plate 144 during pivoting of the jaw members 110 and 120.

[0077] The outer housing of each of the jaw members 110 and 120preferably includes an additional recess or circular groove 129 whichreceives a ring-like insulator 153 b and 153 a, respectively. Insulators153 a and 153 b insulate the pivot pin 150 from the jaw members 110 and120 when the forceps 10 is assembled. Preferably the pivot pin 150 ispeened to secure the jaw members 110 and 120 during assembly and mayinclude outer rims 151 a and 151 b at least one of which is peened orformed after the jaw members 110 and 120 are assembled about the pivotpin 150 as best shown in FIG. 4B.

[0078] Upon activation, the first electrical potential is carried bylead 210 a through tube 60 b to the terminal end 212. The washer 155 ofthe distal connector 300 then conducts the first potential to face plate144 which carries the first potential to sealing plate 122 disposed onthe inner facing surface of jaw member 120. The second potential iscarried by lead 210 b which electrically interfaces with the tube 60 b(by way of crimps 85, 87 and 89) to conduct the second potential toterminal sleeve 138 of jaw member 110. The terminal sleeve 138electrically connects to sealing surface 112 across face plate 134.

[0079]FIG. 8 shows the connection of the cable 210 within the cavity 45b of shaft 12 b. As mentioned above a series of finger-like elements 77a and 77 b and crimps 76 a and 76 b secure the cable 210 within shaft 12b. Preferably, cable 210 is secured at an angle alpha (a) relative to alongitudinal axis “A” disposed along shaft 12 b. It is envisioned thatangling the cable 210 in an inward direction, i.e., towards shaft 12 a,facilitates handling of the forceps 10 and the cable 210 during surgery,i.e., the angled disposition of the cable 210 as it exits the forceps 10tends to reduce cable tangling and/or cable interference duringhandling.

[0080] Preferably at least one of the jaw members 110 and 120 includes askirt-like feature 126 and 136, respectively, which is dimensioned toprevent exposure of the terminal end 212 or wire 211 during all anglesof operation, i.e., when the jaw members 110 and 120 are disposed in thefirst open position, the second closed position and/or during operativemovement therebetween.

[0081] It is envisioned that by making the forceps 10 disposable, theforceps 10 is less likely to become damaged since it is only intendedfor a single use and, therefore, does not require cleaning orsterilization. As a result, the functionality and consistency of thevital sealing components, e.g., the conductive surfaces 112 and 122, thestop member(s) 150, and the insulative housings 124 and 114 will assurea uniform and quality seal.

[0082] From the foregoing and with reference to the various figuredrawings, those skilled in the art will appreciate that certainmodifications can also be made to the present disclosure withoutdeparting from the scope of the present disclosure. For example, it maybe preferable to include a tang which facilitates manipulation of theforceps 10 during surgery.

[0083] Moreover, although the electrical connections are preferablyincorporated with the bottom shaft 12 b and the instrument is intendedfor right-handed use, it is contemplated the electrical connections maybe incorporated with the other shaft 12 a depending upon a particularpurpose and/or to facilitate manipulation by a left-handed user.

[0084] It is also contemplated that a shrink tube may be employed overthe proximal connector 80 and/or the other various solder or crimpconnections 85, 87 and 89 associated with the proximal connector 80interface with lead wire 210 b. This provides additional insulatingprotection during assembly. An insulative sheath may also be used tocover the end effector assembly 100 or the outer surfaces (non-opposingsurfaces) of the jaw members 110 and 120.

[0085] It is also contemplated that the forceps 10 (and/or theelectrosurgical generator used in connection with the forceps 10) mayinclude a sensor or feedback mechanism (not shown) which automaticallyselects the appropriate amount of electrosurgical energy to effectivelyseal the particularly-sized tissue 400 grasped between the jaw members110 and 120. The sensor or feedback mechanism may also measure theimpedance across the tissue during sealing and provide an indicator(visual and/or audible) that an effective seal has been created betweenthe jaw members 110 and 120.

[0086] Experimental results in animal studies suggest that the magnitudeof pressure exerted on the tissue by the seal surfaces 112 and 122 isimportant in assuring a proper surgical outcome. Tissue pressures withina working range of about 3 kg/cm² to about 16 kg/cm² and, preferably,within a working range of 7 kg/cm² to 13 kg/cm² have been shown to beeffective for sealing arteries and vascular bundles. Tissue pressureswithin the range of about 4 kg/cm² to about 6.5 kg/cm² have proven to beparticularly effective in sealing arteries and tissue bundles.

[0087] In one embodiment, the shaft portions are manufactured such thatthe spring constant of the shaft portions 12 a and 12 b, in conjunctionwith the placement of the ratchet interfaces 32 a and 32 b, will yieldpressures within the above working range. In addition, the successivepositions of the ratchet interfaces increase the pressure betweenopposing seal surfaces 112 and 122 incrementally within the aboveworking range.

[0088] It is envisioned that the outer surface of the jaw members 110and 112 may include a nickel-based material, coating, stamping, metalinjection molding which is designed to reduce adhesion between the jawmembers 110, 112 (or components thereof) with the surrounding tissueduring activation and sealing. Moreover, it is also contemplated thatother components such as the shaft portions 12 a, 12 b and the ringholes 18 a, 18 b may also be coated with the same or a different“non-stick” material. Preferably, the non-stick materials are of a classof materials that provide a smooth surface to prevent mechanical toothadhesions.

[0089] It is also contemplated that the tissue sealing surfaces 112 and122 of the jaw members 110 and 120 can be made from or coated with thesenon-stick materials. When utilized on the sealing surfaces 112 and 122,these materials provide an optimal surface energy for eliminatingsticking due in part to surface texture and susceptibility to surfacebreakdown due electrical effects and corrosion in the presence ofbiologic tissues. It is envisioned that these materials exhibit superiornon-stick qualities over stainless steel and should be utilized on theforceps 10 in areas where the exposure to pressure and electrosurgicalenergy can create localized “hot spots” more susceptible to tissueadhesion. As can be appreciated, reducing the amount that the tissue“sticks” during sealing improves the overall efficacy of the instrument.

[0090] The non-stick materials may be manufactured from one (or acombination of one or more) of the following “non-stick” materials:nickel-chrome, chromium nitride, MedCoat 2000 manufactured by TheElectrolizing Corporation of OHIO, Inconel 600 and tin-nickel. Forexample, high nickel chrome alloys and Ni200, Ni201 (˜100% Ni) may bemade into electrodes or sealing surfaces by metal injection molding,stamping, machining or any like process.

[0091] The Inconel 600 coating is a so-called “super alloy” which ismanufactured by Special Metals, Inc. located in Conroe Texas. The alloyis primarily used in environments which require resistance to corrosionand heat. The high Nickel content of Inconel makes the materialespecially resistant to organic corrosion. As can be appreciated, theseproperties are desirable for bipolar electrosurgical instruments whichare naturally exposed to high temperatures, high RF energy and organicmatter. Moreover, the resistivity of Inconel is typically higher thanthe base electrode material which further enhances desiccation and sealquality.

[0092] As mentioned above, the tissue sealing surfaces 112 and 122 mayalso be “coated” with one or more of the above materials to achieve thesame result, i.e., a “non-stick surface”. For example, Nitride coatings(or one or more of the other above-identified materials) may bedeposited as a coating on another base material (metal or nonmetal)using a vapor deposition manufacturing technique.

[0093] One particular class of materials disclosed herein hasdemonstrated superior non-stick properties and, in some instances,superior seal quality. For example, nitride coatings which include, butnot are not limited to: TiN, ZrN, TiAlN, and CrN are preferred materialsused for non-stick purposes. CrN has been found to be particularlyuseful for non-stick purposes due to its overall surface properties andoptimal performance. Other classes of materials have also been found toreducing overall sticking. For example, high nickel/chrome alloys with aNi/Cr ratio of approximately 5:1 have been found to significantly reducesticking in bipolar instrumentation. One particularly useful non-stickmaterial in this class is Inconel 600. Bipolar instrumentation havingsealing surfaces 112 and 122 made from or coated with Ni200, Ni201(˜100% Ni) also showed improved non-stick performance over typicalbipolar stainless steel electrodes.

[0094] While several embodiments of the disclosure have been shown inthe drawings, it is not intended that the disclosure be limited thereto,as it is intended that the disclosure be as broad in scope as the artwill allow and that the specification be read likewise. Therefore, theabove description should not be construed as limiting, but merely asexemplications of preferred embodiments. Those skilled in the art willenvision other modifications within the scope and spirit of the claimsappended hereto.

What is claimed is:
 1. A bipolar electrosurgical instrument for use inopen surgery, comprising: first and second shafts each having a jawmember extending from a distal end thereof and a handle disposed at aproximal end thereof for effecting movement of the jaw members relativeto one another from a first position wherein the jaw members aredisposed in opposable, spaced relation relative to one another to asecond position wherein the jaw members cooperate to grasp tissuetherebetween, each of the jaw members including an electricallyconductive sealing surface; a source of electrical energy having firstand second electrical potentials, the first electrical potential beingconnected to one of the jaw members and a second electrical potentialbeing connected to the other of the jaw members such that the jawmembers are capable of selectively conducting energy through tissue heldtherebetween to effect a seal, wherein the first electrical potential istransmitted through the first shaft by a lead having a terminal endwhich electrically interfaces with a distal connector which connects oneof the jaw members to the first electrical potential; and at least onenon-conductive stop member disposed on the electrically conductivesealing surface of at least one of the jaw members which controls thedistance between the electrically conductive sealing surfaces whentissue is held therebetween.
 2. A bipolar electrosurgical instrument foruse in open surgery according to claim 1 wherein the at least onenon-conductive stop creates a gap between the electrically conductivesealing surfaces within the range of about 0.001 inches to about 0.006inches.
 3. A bipolar electrosurgical instrument for use in open surgeryaccording to claim 1 wherein the non-conductive stop creates a gapbetween the electrically conductive sealing surfaces within the range ofabout 0.002 inches to about 0.003 inches.
 4. A bipolar electrosurgicalinstrument for use in open surgery, comprising: first and second shaftseach having a jaw member extending from a distal end thereof and ahandle disposed at a proximal end thereof for effecting movement of thejaw members relative to one another from a first position wherein thejaw members are disposed in opposable, spaced relation relative to oneanother to a second position wherein the jaw members cooperate to grasptissue therebetween, each of the jaw members including an electricallyconductive sealing surface; a source of electrical energy having firstand second electrical potentials, the first electrical potential beingconnected to one of the jaw members and a second electrical potentialbeing connected to the other of the jaw members such that the jawmembers are capable of selectively conducting energy through tissue heldtherebetween to effect a seal, wherein the first electrical potential istransmitted through the first shaft by a lead having a terminal endwhich electrically interfaces with a distal connector which connects oneof the jaw members to the first electrical potential; at least onenon-conductive stop member disposed on the electrically conductivesealing surface of at least one of the jaw members which controls thedistance between the electrically conductive sealing surfaces whentissue is held therebetween; and a ratchet disposed on the first shaftand at least one complimentary interlocking mechanical interfacedisposed on the second shaft, the ratchet and the complimentaryinterlocking mechanical interface providing at least one interlockingposition to maintain a closure pressure in the range of about 3 kg/cm²to about 16 kg/cm² between the electrically conductive sealing surfaces.5. A bipolar electrosurgical instrument according to claim 4 wherein theratchet and the complimentary interlocking mechanical interface provideat least one interlocking position to maintain a closure pressure in therange of about 7 kg/cm² to about 13 kg/cm² between the electricallyconductive sealing surfaces.
 6. A bipolar electrosurgical instrumentaccording to claim 4 further comprising a non-stick material disposed onthe electrically conductive sealing surfaces.
 7. A bipolarelectrosurgical instrument according to claim 4 wherein thenonconductive stop member is disposed adjacent the electricallyconductive sealing surfaces.
 8. A bipolar electrosurgical instrumentaccording to claim 6 wherein the nonstick material is a coating which isdeposited on the electrically conductive sealing surfaces.
 9. A bipolarelectrosurgical instrument according to claim 8 wherein the nonstickcoating is selected from a group of materials consisting of: nitridesand nickel/chrome alloys.
 10. A bipolar electrosurgical instrumentaccording to claim 8 wherein the nonstick coating includes one of TiN,ZrN, TiAlN, CrN, nickel/chrome alloys with a Ni/Cr ratio ofapproximately 5:1, Inconel 600, Ni200 and Ni201.
 11. A bipolarelectrosurgical instrument according to claim 6 wherein the electricallyconductive sealing surfaces are manufactured from a non-stick material.12. A bipolar electrosurgical instrument for use in open surgery,comprising: first and second shafts each having a jaw member extendingfrom a distal end thereof and a handle disposed at a proximal endthereof for effecting movement of the jaw members relative to oneanother from a first position wherein the jaw members are disposed inspaced relation relative to one another to a second position wherein thejaw members cooperate to grasp tissue therebetween, each of the jawmembers including an electrically conductive sealing surface; a sourceof electrical energy having a first electrical potential connected toone of the jaw members and a second electrical potential connected tothe other of the jaw members such that the jaw members are capable ofselectively conducting energy through tissue held therebetween to effecta seal; the first and second electrical potentials being transmitted tothe jaw members through the first shaft wherein the first electricalpotential is transmitted by a lead having a terminal end whichelectrically interfaces with a spring washer, the spring washer actingas an electrical intermediary between the terminal end and the jawmember; at least one non-conductive stop member disposed on theelectrically conductive sealing surface of at least one of the jawmembers which controls the distance between the jaw members when tissueis held therebetween, wherein the at least one non-conductive stopcreates a gap between the electrically conductive surfaces within therange of about 0.001 inches to about 0.006 inches; and a ratchetdisposed on the first shaft and at least one complimentary interlockingmechanical interface disposed on the second shaft, the ratchet and thecomplimentary interlocking mechanical interface providing at least oneinterlocking position to maintain a closure pressure in the range ofabout 3 kg/cm² to about 16 kg/cm² between the electrically conductivesealing surfaces.